The doFilterEvent method of the HttpEventFilter is called by the container
each time a request/response pair is passed through the chain due
to a client event for a resource at the end of the chain. The HttpEventFilterChain passed in to this
method allows the Filter to pass on the event to the next entity in the
chain.

A typical implementation of this method would follow the following pattern:-
1. Examine the request
2. Optionally wrap the request object contained in the event with a custom implementation to
filter content or headers for input filtering and pass a HttpEvent instance containing
the wrapped request to the next filter
3. Optionally wrap the response object contained in the event with a custom implementation to
filter content or headers for output filtering and pass a HttpEvent instance containing
the wrapped request to the next filter
4. a) Either invoke the next entity in the chain using the HttpEventFilterChain
object (chain.doFilterEvent()),
4. b) or not pass on the request/response pair to the next entity in the
filter chain to block the event processing
5. Directly set fields on the response after invocation of the next entity in the filter chain.

Parameters:

event the event that is being processed. Another event may be passed along the chain.